Megastigmatrienone [as a 3,5,5-trimethyl-4-(2-butenylidene)cyclohex-2-en-1-one mixture of isomers] is a component of Burley, Turkish and Greek tobacco, as reported in Tobacco Science, 16, 107 (1972); Helv. Chim. Acta, 55, 1866 (1972); Acta Chem. Scand., 26, 2573 (1972); and Tobacco Science, 18, 43-48 (1974), and contributes to the overall flavor characteristics of tobacco. Megastigmatrienones as a class of natural fragrant tobacco components are described in U.S. Pat. Nos. 4,753,924 and 4,827,012.
Megastigma-4,6,8-trien-3-one(1) can be considered a dehydration product of 3-oxo-.alpha.-ionol(2), which also is a constituent of tobacco: ##STR2## Megastigma-4,6,8-trien-3-one has a tendency to polymerize, and is a difficult chemical compound to store or formulate.
Of background interest with respect to the present invention are technical publications concerned with thermolysis of oxalate esters. Pyrolysis studies of oxalate esters such as benzyl oxalates and diallyl oxalates are reported by W. S. Trahanovsky and coworkers in publications which include J. Org. Chem., 32, 2287 (1967); J. Am. Chem. Soc., 90, 2839 (1968); Tetrahedron Lett., 3627 (1968); J. Am. Chem. Soc., 92, 7174 (1970); J. Org. Chem., 36, 3575 (1971); and Chem. Commun., 102 (1971). The thermal decomposition of dialkyl oxalates is described by G. J. Karabatsos et al in J. Org. Chem., 30, 689 (1965) and J. Am. Chem. Soc., 91, 3324 (1969).
It is characteristic of organic compounds employed as tobacco flavorants in the prior art that the respective derivatives have the disadvantage of both high volatility and low odor threshold. Both of these properties significantly restrict the extent that these organoleptic materials can be utilized as flavorants in tobacco compositions.
There is continuing research effort to develop improved smoking compositions which contain a new and efficient low volatility flavorant-release additive, and which generate mainstream smoke with natural flavorant-enhanced taste and character under smoking conditions.
Accordingly, it is an object of this invention to provide smoking compositions having incorporated therein a flavorant component which is characterized by lack of mobility and/or volatility at ambient temperature.
It is another object of this invention to provide smoking compositions having incorporated therein a flavorantrelease additive which under normal smoking conditions yields pyrolysis constituents which impart improved natural tobacco flavor to mainstream smoke and improved aroma to sidestream smoke.
It is a further object of this invention to provide novel oxalate compounds of low volatility which are adapted to b incorporated into cigarette fillers, and which under normal smoking conditions release a natural tobacco flavorant constituent into cigarette smoke.
Other objects and advantages of the present invention shall become apparent from the following description and examples.